What is cufon and canvas and how to overwrite them

In my Wordpress theme I had a hover effect on my top menu but then it suddenly stopped working and I don't know why, so I tried to inspect element to see what was going on and also tried to add a css class like this to try to get the over effect back:

#navigation li a:hover{color:#b0d719 !important;}

But it's not working, then I realized something in html... those cufon and canvas thing which I don't know what it is and also don't know how to overwrite them to accomplish this to get the hover effect back again on the navigation bar.

Here's my website link and here's a image preview where this is happening as well

Well after a few tests removing shorts of codes and stuff I just figured it out. I had this code above of all of those JS scripts and CSS as well in header

<script src="//code.jquery.com/jquery-1.10.2.js"></script>
<script type="text/javascript">
// document ready equivalent
$(function(){
   // hide
   $( "#share-stuff" ).hide();

   $( "#clickme" ).click(function() {
    $( "#share-stuff" ).slideToggle( "slow", function() {
     // Animation complete.
    });
  });
});
</script>

Then I removed it and the hover effect worked well, so I moved this to below of all of the Js and CSS placed in the header and it is working now, but still don't know why is this, neither what's the reason of doing that, still I would like to know